Handle empty view with AdapterDataObserver

[phatnhse]

Hi team, please take a look at this function

If I set empty adapter at the first time view created

1. updateHelperDisplays will be called
2. isFirstLoadingOnlineAdapter will become true, and there is nowhere to set it false again
3. if mEmptyView is not null and data size = 0, then mEmpty will be gone?

Correct me if I am wrong: Lately when I call notifyDataSetChanged(), the function above (in red square) will never call again, so there is no change for mEmpty be visible again?

Expected: When data change, the empty view should be visible/gone base on data size. I don't want to use show/hide empty view explicitly, it will be painful to control states. Because UltimateRecyclerView already has AdapterDataObserver so I expect it could update UI base on data size.

Thanks